1. Field of the Invention
The present invention relates to energy conversion devices and more particularly to devices for converting between thermal and electrical energy through the use of semiconductor or insulator and conductor structures.
2. Description of the Prior Art
In the prior art, there are many devices which convert thermal energy to electrical energy.
One such device is the thermionic converter. The thermionic converter generally comprises a cathode made from a highly emissive material or composition of material, an evacuated space or a low pressure gas plasma filled space and an anode for collecting electrons emitted by the cathode.
The efficiency of thermionic converters is generally low, in the order of 10 to 20 percent, and the lifetime is limited, based upon the capacity of the cathode to emit electrons and remain stable at the high temperatures required for operation.
While there are in the prior art some thermionic diodes which use semiconductor material, the semiconductor material, in the past, has been used to enhance the electron emissive capability of the cathode structure of the thermionic device.